hi all i got a Ef 5 speed and i was thinking what brake rotors to put on it? i have heard different stories about DBA gold (drilled and slotted) that they get cracks around where they have been drilled. i have not heard much about the DBA slotted. what are they like? what other brands are good that are out there?

thanks

I can see your new so I'll help you out

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There have been a few negative posts about drilled rototrs. I was advised from a few brake experts against them unless your a Mum and Dad type driver.

I would however suggest the DBA slotted 4000 Club Spec series rotors over the standard type. These are heat treated and won't warp.

Drilled rotors are also noisy, you get an annoying whooshing sound as air flows through the holes. Slotted rotors are fine for a street car.

The problem with drilled rotors as I see it is this.

When you cross drill or slot a rotor, you're reducing the surface area of the disk which means you need a greater pad pressure on the rest of the disk. This leads to more heat. Also, when you get better brakes, you're more lively with your breaking which leads to high brake temps and a faster rise in the brake temps.

This faster rise leads to metal fatigue. You can fatigue a set of standard rotors, but it's much easier to do on cross driled because the drilling reduces the strength of the disk and also creates a weak point between the holes.

Racing drivers don't get this problem with disks as the disks only last one race generally, plus they're kept up to operating temperature all the way through the race and are not subjected to the harsh rise and fall in brake temps that road discs are subjected to.

Brake temps on a road car can go from ambient temps, 25C, to around 500C very easily if you stand on the brakes @ 110km/h. It puts a massive thermal shock through the disc which leads to all the problems.

But, if you're concious of this fact, and warm up your brakes if you intend to do some spirited braking, and also let them cool down properly after your fun, you shouldn't have any trouble with them.

EBC have a range of slotted rotors wich are blind drilled instead of through drilled. These seem to be a better option as they would not suffer from all the problems that through drilling has.

Dude...

Drilling and slotting rotors was done in days of yore when
brake pads gave off gas under extreme heat.
the gassing off would cause the pads to "fly" over the rotors,
and thus cause a loss of stopping power...

yer modern brake pads are made of materials that
don't gas off.....(now we just need some politicians made of that stuff)

The trade off was that the rotors cracked around the
drill holes and/ or the slots...
and was really only worth the effort for race teams
who could afford new rotors every race.

the slots also act as an ablative - in other words
they plane down the surface of the pad, preventing
glazing, but wear the pads quicker as a result.

A mate who works at DBA (no names please!) told me
the drilled and or slotted stuff is sold primarily as
an aesthetic thing......the 'long life' jobbies are the go
for both street and track.


cheers,

Really?

I'll be keeping my DBA slotted discs all round thanks. Yeah they're harsher on the pads, but heck, I want to be able to pull up the best I can (given the rather poor stock brakes on EF/ELs) And having the ability to get more 'bite' into the pad certainly helps.

Also, over the Ford discs where I was replacing them (and pads) every 10,000Ks, while I'm now only just onto my second set of DBA slotteds, the first set gave me 3 sets of pads, and 57,000Ks

What the heck... You must dricve pretty crazy if you were going through standard pads that quickly!

I do regular track work.

i have a friend who ownes a ea 5 speed (well modded) and he has dba slot/drill and he pulls up from high speen really REALLY well, p.s. no whooshy sounds.

i got a quote from "Hoppers Stoppers" in Werribee, and they said that drilled are worse for the ef/el, and gave me a quote for $370 for two slotted discs, and some 650Deg pads, fitted.

P.S. $20 for drilled upgrade.

The slotted definately help with preventing glazing. After Phillip Island the front -slotted felt ok and the rear -not slotted took another 1000km's to unglaze. This is with lucas pads.

Soon to be going in for slotted rears and EBC all round.

Well lucas are a pretty budget sort of pad...ive got them on the car now just in the meantime until the 4 pot kits are finished. Lucas around $55 for the front compared to EBC green at $115 for the front.

And back to the topic mate depends on the application if u just like to cruise around and dont wanna spend much just get slotted...if u wanna spend a bit mmore for the look factor get drilled but if your gonna be thrashin the car on the track then slotted is gonna last longer and be stronger....tho track work depending on how frequent you will probably be going through some rotors anyhow

I beg to differ. More modern pads fade at a mugh higher temperature. Ultimates for instance fade at about 650C. This does not meen that they don't 'gas off' Get ANYTHING hot enough and it will convert to its gaseous state. Get it even hotter, and you make plasma!

It's just that with older pads, like the old Bendix pads with asbestos, the fade temp was mor along the lines of 300C which is more than attainable on a road car without much trouble at all.

Last time I faded pads on a Falcon, the pads faded @ about 400C according to the manufacturer and you could see plumes of black dust and gasses pouring out of the wheels. Quite fun actually!

Last edited by unclewoja on Wed Oct 12, 2005 12:42 pm, edited 1 time in total.

That goes against all the independant and DBA tests that show a significant decrease in stopping distance with slotted rotors. Personally I noticed a huge difference when I upgraded to slotted and drilled rotors. As for the cracking, I have run mine really hard for 5 years now and they are still fine. I do believe that there were some issues when they first cam on the market, but they have now been around for close to 10 years and I have not heard of any issues recently.

Also worth noting that DBA slotted rotors are not suppose to be used with EBC pads, I think thats where a lot of problems come from.

i got slotted and there ace